1. Field of the Invention
The present invention relates to an information recording method and its device and is suitably applied to an information recording method and its device to write data on a write once read many (WORM) disc recording medium on a fixed data basis for example.
2. Description of the Related Art
Heretofore, there has been a read only memory disc called as CD-ROM (compact disc-read only memory) as a large capacity data recording medium. The file system exclusively for CD-ROM has been used in this CD-ROM.
There has been a recordable disc shaped recording medium called as CD-R (compact disc-recordable) which enables write once by forming new recording layer on this CD-ROM. In this CD-R, data will be recorded/reproduced using the packet recording file system for the CD-R in place of the file system for the CD-ROM described above.
As a recording method of this kind, as shown in FIG. 1, the file system of the host computer side, after collecting one packet of data at step SP1, moves to step SP2, and as well as sending a write command of the packet to the CD-R drive device side, transmits the data of said packet (write data) to the CD-R drive device side.
At step SP3, the CD-R drive device moves a pickup a little toward this side from the write position designated to the write data transmitted at the step SP2 and starts the reproduction by tracing the recording track from that position.
Then, at step SP4 the CD-R drive device waits until the drive servo of the CD-R disc becomes stable, and moving to step SP5, it makes the signal recorded on the CD-R disc to synchronize with the data to be recorded on the CD-R disc hereafter at an encoder. Then, the CD-R drive device moves to step SP6 and starts encoding faster for the data delay at the encoder, and at step SP7, when the pickup reaches the predetermined write position, the CD-R drive device increases the laser output and writes the write signal supplied from the encoder on the disc. Thus, the CD-R drive device executes the setup at steps SP3-SP7 before starting the actual data writing.
When the data writing is started at the step SP7, the CD-R drive device moves to step SP8, and when completing the encoding for one packet and reaching to the predetermined write stop position, it stops the write function by decreasing the laser output. Thus, the data writing for one packet in the CD-R drive device is completed, and at this moment the CD-R drive device moves to step SP9 and by transmitting the success of said packet writing to the file system, one packet of data writing is completed.
With this arrangement, whenever the data writing for one packet is completed, the CD-R drive device informs the completion of writing to the file system side and as shown in FIG. 2, every time said information is received, the file system collects succeeding one packet of data and repeats steps SP1-SP9 described in FIG. 1.
However, in order to write data per packet on the CD-R disc according to the method described above, the file system starts the processing to collect the succeeding packet data at the time when the write operation of each packet shown in FIG. 2 (steps SP3-SP9) is completed. And thus, the operation of the file system side is suspended during the data writing process at the CD-R drive device side (steps SP3-SP9), and it becomes inevitable that the overall writing operation requires lengthy processing period. Especially, the CD-R disc device has slower seek speed than the hard disc device and since the time needed for setup (steps SP3-SP7) described in FIG. 1 becomes lengthy and during this period the file system is forced to wait for the processing. As a method to solve this problem, the method to send back the write success information using write cache before the actual data writing can be considered. More specifically, in FIG. 3 in which the corresponding parts of FIG. 1 are given the same reference numerals, the file system of the host computer side compiles one packet of write data in the buffer at the step SP1 and sends out the write command and write data of said packet to the CD-R drive device at the step SP2. When the CD-R drive device receives the write command and the write data supplied from the file system side at the step SP2, at the step SP9 before starting to write data, it sends back the write success information of the packet designated to write by said write command (i.e., the write command complete information of said packet) to the file system side. Thus, the processing to collect data of the packet succeeding said packet will be started.
When the CD-R drive device returns the write success information (command complete information) to the file system at the step SP9, it moves to the step SP3 and starts an actual write processing of write data of the packet of which success information is returned ahead of time at the step SP9.
More specifically, at the step SP3, the CD-R drive device moves the pickup toward this side a little from the write position designated and starts reproduction by tracing the recording track from that position.
Then, at the step SP4, the CD-R drive device waits until the drive servo of the CD-R disc becomes stable, and moving to step SP5, synchronizes the signal recorded on the CD-R disc with the data to be recorded hereafter on the CD-R disc at the encoder. Then, the CD-R drive device moves to the step SP6 and starts encoding faster for the data delay at the encoder, and at the step SP7, when the pickup reaches to the predetermined write position, increases the laser output and writes the write signal supplied from the encoder on the disc. Thus, when the setup of steps SP3-SP7 has been completed, data writing will be started, and moving to the step SP8, the CD-R drive device completes encoding for one packet and when reaching to the write stop position, it stops the write operation decreasing the laser output. Thus, the data writing for one packet in the CD-R drive is completed.
With this arrangement, by executing the processing of step SP9 before the setup of steps SP3-SP7 is conducted and sending back the write success information of the packet of which write process has not been started to the file system side, the file system can start the processing to compile data of the packet succeeding the packet on which said write processing is conducted before the completion of actual writing (i.e., before setup) at the step SP8.
The method to record data sequentially on the CD-R disc in utilizing the write cache process can be considered. More specifically, as shown in FIG. 4A, the file system of the host computer side compiles data sequentially on a packet-by-packet basis using the write cache process described above in FIG. 3 to the buffer memory of the CD-R drive device side. At this time the buffer memory of the CD-R drive device writes said data on the CD-R disc sequentially until the stored data would be used up, and as shown in FIG. 4B, when the data in the buffer memory is gone, writes run out information RO1 and RO2 showing the completion of the packet making the data written on the CD-R disc as one packet and completes the data writing. Thus, the writing method which writes data for one data track sequentially as shown in FIG. 5, the so-called track at once, can be considered.
However, if the write cache shown in FIG. 3 is used on the file system side, write success information is sent back from the CD-R drive device to the file system of the host computer before the write data is actually completed, and accordingly, the file system side starts preparation for the next packet destroying the data before the completion of write data. Therefore, if the actual write data is failed, the restoration of data becomes difficult.
Furthermore, as shown in FIG. 4, in the case where the CD-R drive device side forms variable length packets by successively conducting the write data until data in the buffer memory is used up, the length of said write packet to be written actually on the CD-R disc depends on the data volume of the buffer memory of the CD-R drive device and it is difficult to recognize the length of said packet in the file system of the host computer side. When the variable length packet formed on the CD-R disc is completed, the complete information, so-called lead out, is written on the edge of said packet and simultaneously, when the following packet data writing is started, link block showing the border of packets and lead in information of 4 blocks showing the packet starting information are written. Accordingly, in the case where the packets are completed corresponding to the data volume of the buffer memory of the CD-R drive device side, the write position of the following packet shifts for ring block and the preceding and succeeding lead out block and lead in block, that is address shift occurs. This address shift can be hardly recognized by the file system side and as a result, the difference existed between the write address to be recognized on the file system side and the address in which actually data is written.